This invention relates generally to thrust bearings with rollers and, more particularly, to a thrust washer having anti-reversal and anti-rotation features for use in such thrust bearings.
Thrust bearings with rollers are intended to transmit thrust through the rolling elements, typically rolling on raceways of two opposed thrust washers, without sliding of the thrust washers along their respective backup surfaces. Such sliding may be a problem, particularly when a backup surface is made of a material that is softer than the preferred hardened steel, such as unhardened steel, aluminum or even plastic, for example. In such applications, a simple tab extending radially outwardly from the thrust washer would cut into the backup material rather than prevent relative rotation.
Generally, the two thrust washers of such thrust bearings are not identical, and many applications require such thrust bearings to be installed with a particular one of the two thrust washers against a respective mating surface. That is, assembly of the transmission or other device requires installation of the thrust bearing assembly in a particular orientation, or, in other words, not xe2x80x9cbackwardsxe2x80x9d. Accordingly, there is a need for a thrust washer with both an anti-rotation device and an anti-reversal device suitable for use with relatively soft backup materials.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
In one aspect of the invention, this is accomplished by providing a thrust washer formed from metal sheet and comprising a flat, ring-shaped thrust portion oriented radially with respect to an axis and including a raceway for rollers, and at least one tab extending from an outer or inner perimeter of the thrust washer. The tab includes a radially oriented mid-portion and at least one wing-portion extending perpendicular to the mid-portion and parallel to the axis of the thrust portion such that a flat surface of the wing-portion may engage a recess of a backup member to prevent rotation of the thrust washer relative to the backup member. The tab is not symmetrical about a line along a diameter of the thrust portion but is xe2x80x9coffsetxe2x80x9d therefrom.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.